The invention relates generally to shielding structures, and, more particularly, to such shielding structures which are capable of protecting spacecraft components from critically damaging impact with a variety of space particles having a wide range of velocities and angles of approach such as meteorites and orbital debris. The invention addresses the fact that each impact causes some degree of damage to the shield itself and this damage can range from small holes in the outer protective layers to large (several inches in diameter) holes in the underlying protective layers. The invention incorporates elements that provide some degree of protection for subsequent impacts following the widespread damage to the shield system commensurate with defeat of the "design-size" particle.
Many different types of shields have been designed for protecting many types of vehicles as well as personnel from impact with ballistic projectiles and other types of impacting particles. Many of these shields include layers of fabric bonded together. An example of such a shield is disclosed in U.S. Pat. No. 4,923,741 to Kosmo. The Kosmo shield is specifically designed for spacesuits and spacecraft and has layers of fabric composed of low density and high density material which provide micrometeorite protection, radiation protection, etc. Some of these fabric layers include aramid fibers. However, a primary disadvantage of the Kosmo shield is that although it provides for a variety of different types of protection including radiation and thermal extremes, it is incapable of providing protection against both high and low velocity particle collisions.
Other prior art shields have been designed specifically for protecting personnel, equipment and vehicles from injury and damage caused by projectiles, bomb fragments and other products of explosives. An example of such a prior art shield for suppressing or reducing penetration by such particles is disclosed in U.S. Pat. No. 3,924,038 to McArdle. The McArdle design utilizes a ceramic outer layer and nylon felt layers backed by a metallic layer. The felt layers are stitched together into a cloth-like configuration. However, a primary disadvantage of such a shield is that it provides protection only against relatively low velocity particles such as bullets. The selection of the different types of materials used in the McArdle design is specifically to allow effective shielding against a variety of shapes and sizes of particles rather than against particles having a wide range of velocities.
Another type of prior art shield design includes various shielding layers which are separated from the particular structure to be shielded. An example of such a shield is disclosed in U.S. Pat. No. 3,569,714 to Anderson. The Anderson shield provides protection from a variety of hazards including impacts with projectiles, temperature extremes and radiation. The Anderson shield includes a plurality of chambers positioned so that one is within the other and includes an open space between the outer and inner containers. However, as with the other prior art patented designs discussed hereinabove, the Anderson shield does not provide protection against a variety of high and low velocity impacting particles. Moreover, due to the particular mounting configuration and the particular shapes of the containers, the Anderson shield additionally has the disadvantage of not being able to provide protection equally from particles impacting the protected structure from all directions.
Other prior art patents for providing shielding for space and atmospheric vehicles include shells which are provided with inner walls therebetween. The inner walls define an area containing a material for providing protection against collision with projectiles. Such a shield is disclosed in U.S. Pat. No. 3,439,885 to Sackleh. The Sackleh shield incorporates bronze wool in the area and supports which are rods or ribs positioned between the outer and inner shells. The bronze wool is utilized to provide protection from low velocity projectiles. However, the outer shell is simply utilized to provide a smooth outer surface for the bronze wool which is the primary protection provided against projectile impacts. Consequently, as with the other prior art patents discussed hereinabove, the Sackleh shield does not provide protection against both high and low velocity particles.
What is therefore needed is a shield for spacecraft that provides generally complete protection against impacts from micrometeoroids and orbital debris particles having a wide range of impact velocities and angles of approach.